stem-group bilaterians Hatschek, 1888 - bilaterians see Subkingdom Bilateria Hatschek, 1888 Family †Siphusauctidae O'Brien & Caron, 2012 Genus †Siphusauctum O'Brien & Caron, 2012 †Siphusauctum gregarium O'Brien & Caron, 2012